1. Field of the Invention
The present invention relates to absorption/isolation of vibrations in internal combustion engines, and is more particularly directed to crankshaft provided with vibration dampening members for absorbing/isolating vibrations between a crankshaft and a connecting rod and/or a cylinder block of an internal combustion engine.
2. Description of the Prior Art
In the conventional multi-piston type internal combustion engine the pistons are coupled to a crank shaft by connecting rods to translate the reciprocating motion of the pistons to the rotary motion of the crankshaft. Explosions in the combustion engine create vibrations which are transmitted to the connecting rods and from the connecting rods to the crankshaft to a cylinder block. These vibrations increase in force and frequency in high speed engines.
Conventionally, the connecting rods which house rod bearings are separated from a rod journal by a thin layer of lubricating oil. Similarly, the sides of the connecting rod are bathed in lubricating oil preventing contact with the crankshaft. Because of the relative incompressibility of this oil layer, vibrations are easily transmitted from the connecting rod/bearing assembly to the crankshaft and from the crankshaft to the cylinder block causing maintenance problems and wearing and tearing the engine.
In order to alleviate this problem, prior art engines incorporate various vibration dampening devices. However, most of the vibration dampening devices of the prior art suffer from the drawback that they are located far from the source of the vibrations.
Therefore, there is a need for a vibration absorbing/isolating device for an internal combustion engine located close to the source of the vibrations to alleviate most of the drawbacks of the prior art in a simple, efficient and inexpensive manner.
The present invention provides a vibration dampener assembly provided to isolate vibrations between connecting rods and a crankshaft and/or between a crankshaft and a cylinder block of an internal combustion engine and prevent/reduce vibrations from being transmitted to the crankshaft and/or to the cylinder block and, consequently, to remaining portions of a drive train assembly.
The internal combustion engine in accordance with the present invention comprises the crankshaft having at least one rod journal and at least one main journal, the cylinder block including at least one crankshaft support member rotatably supporting the at least one main journal the crankshaft, and at least one connecting rod rotatably coupled to the at least one rod journal of the crankshaft. Preferably, the internal combustion engine in accordance with the preferred embodiment of the present invention comprises the crankshaft having a plurality of the rod journal and a plurality of the main journal, a plurality of the crankshaft support members and a plurality of the connecting rods.
Each of the crankshaft support member comprises a main bearing portion, which may be integrally formed within the engine block, and a main bearing cap connected to the corresponding main bearing portion to circumscribe the main journal of the crankshaft through semi-cylindrical main bearings. Moreover, each of the crankshaft support members has a main bore defined by an inner wall of the main bearing portions disposed between two axially opposite chamfered ends and a complementary inner wall of the main bearing cap also disposed between two axially opposite chamfered ends.
Each of the connecting rods in accordance with the present invention, has a split first end adapted for holding the rod journal of the crankshaft and connecting rod bearings, and a second end defining a pin opening provided to receive a piston pin. The first end has a crank bore adapted for receiving the rod journal of the crankshaft and the connecting rod bearings, and defined by an annular, substantially cylindrical inner wall disposed between two axially opposite chamfered ends.
In order to effectively reduce and eliminate the transmission of vibration and its harmonics from the connecting rod to the crankshaft and/or from the crankshaft to the cylinder block, a vibration dampener assembly is disposed between the connecting rod and the crankshaft and/or between the crankshaft and the cylinder block.
The vibration dampener assembly in accordance with the preferred exemplary embodiment of the present invention comprises a pair of substantially annular recessed portions formed in an outer peripheral surface of each of the rod journals of the crankshaft, a pair of axially spaced, opposite, substantially annular recessed portions formed in the outer peripheral surface of each of the main journal of the crankshaft, and a plurality of a pair of complementary, substantially annular vibration dampener members each pair disposed in the corresponding, annular recessed portions formed in the journal bearings and the main bearings of the crankshaft respectively, for thereby dampening a transmission of vibrations between the crankshaft and the connecting rods and between the crankshaft and the cylinder block. Alternatively, any appropriate number of the annular vibration dampener members may be mounted to the rod journals and the main journals of the crankshaft. Preferably, the annular recessed portions are formed on the axially opposite end sides of the rod journal adjacent to the counterweights. Similarly preferably, the annular recessed portions are formed on the axially opposite end sides of the main journal adjacent to the counterweights.
Preferably, the vibration dampener members mounted to the rod journals of the crankshaft slightly extend from the recessed portions in the rod journals of the crankshaft so that the vibration dampener members are in contact and somewhat compressed by the chamfered ends of the crank bore of the connecting rod, thus significantly dampening a transmission of vibrations from the connecting rod to the crankshaft. Similarly preferably, the vibration dampener members mounted to the main journals of the crankshaft slightly extend from the recessed portions in the main journals of the crankshaft so that the vibration dampener members are in contact and somewhat compressed by the chamfered ends of the main bearing blocks and the main bearing caps, thus significantly dampening a transmission of vibrations from the crankshaft to the cylinder block.
Preferably, the two pairs of vibration dampener members together form O-ring-like rings and have substantially circular cross-section. Correspondingly, the semi-annular recessed portions have substantially semi-circular cross-sections substantially complementary to the cross-sections of the vibration dampener members. Further preferably, the vibration dampener members are made of a slippery elastomeric oil resistant rubber-like material.
Moreover, previously manufactured internal combustion engines having conventional crankshafts, may be easily retrofitted with the crankshafts of the present invention.
Those skilled in the art will also understand that the crankshaft of the present invention can be used in many different types of mechanisms, other than the internal combustion engines, employing the connecting rod/crankshaft combination, such as piston pumps, pneumatic or hydraulic piston actuators, etc.
Therefore, the present invention provides a simple and inexpensive vibration dampener arrangement for isolating/reducing the engine vibrations at their source, i.e. between the connecting rods and the crankshaft, before they are transmitted through the crankshaft to the other components of the engine, and between the connecting rod and the cylinder block, and prevent/reduce the vibrations from being transmitted to the crankshaft and/or to the cylinder block and consequently to the remaining portions of the drive train assembly.